Any idea about which plants we are prohibited from cultivating according to Indian law ?
Yes, opium and marijuana are not allowed 
Not without a valid licence anyways.
On a serious note, other than narcotics no plants are prohibited per say, if you can shed more light on which plants were you planning to grow that prompted you to ask this question, maybe you can get a better response…
Gosh, we are NEVER visiting your farm even on invitation! 
Hopefully it’ll be safe inside so you can come anytime !
why poisonous plants,after doing online research and consulting few experts i decided to plant karonda plants for fencing.its fruit can be sold in vegetable markets,it is used both as a vegetable and in pickles.it is draught hardy,means dont need much watering.once the plants are established,their roots will survive on rainfall or occasional watering.
it gets spikes,so no human or animal can enter your farm.
Actually, I was trying to find info about which plants can be used for fencing and came across this link: ethnoleaflets.com/leaflets/fencing.htm
I didn’t know most of the plants, so tried looking them up and it seemed to me that this one is really dangerous. So I automatically wondered if it was legal to plant such things?
Even I wanted to know if there are such plants which are prohibited then are they in some list of plants that the government has formulated or rules which explains them more ellaborately.